CN113170256A

CN113170256A - Coaxial waveguide

Info

Publication number: CN113170256A
Application number: CN201980078798.2A
Authority: CN
Inventors: G·J·扎斯图皮尔; J·J·库蒂尔; G·L·默里
Original assignee: Bose Corp
Current assignee: Bose Corp
Priority date: 2018-11-30
Filing date: 2019-11-25
Publication date: 2021-07-23
Also published as: EP3888378A1; US10694281B1; JP2022510222A; WO2020112653A1; US20200177988A1; JP7342123B2

Abstract

Various implementations include a speaker. In some particular cases, the speaker includes: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; and a waveguide covering the acoustic radiation surface of the LF driver, the waveguide having an aperture pattern such that the acoustic radiation pattern of the LF driver matches the acoustic radiation pattern of the HF driver at a reference position.

Description

Coaxial waveguide

Technical Field

The present disclosure relates generally to speakers. More particularly, the present disclosure relates to a speaker having a coaxial waveguide for controlling the sound radiation pattern from a low frequency driver and a high frequency driver.

Background

There is an increasing demand for thin speaker applications. However, as the depth of the speaker decreases, the distance between the low frequency driver (woofer) and the high frequency driver (tweeter) decreases, which can present acoustic challenges. For example, the beamwidth of the low frequency driver may be difficult to control under these conditions. Conventional speakers do not address these challenges.

Disclosure of Invention

All examples and features mentioned below can be combined in any technically possible manner.

Various implementations include a speaker with a coaxial waveguide. In additional implementations, a coaxial waveguide is used to control the acoustic output of the speaker.

In some particular aspects, a speaker includes: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; and a waveguide covering the acoustic radiation surface of the LF driver, the waveguide having an aperture pattern such that the acoustic radiation pattern of the LF driver matches the acoustic radiation pattern of the HF driver at a reference position.

In another aspect, a speaker includes: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; a waveguide covering the acoustic radiation surface of the LF driver, the waveguide having a plate with a plurality of holes extending axially therethrough, wherein the acoustic radiation pattern of the LF driver matches the acoustic radiation pattern of the HF driver at a reference position; and a batting positioned between the waveguide and the LF driver, wherein the batting controls cavity resonance between the LF driver and the waveguide.

In a further aspect, a method comprises: providing a speaker having: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; and a waveguide covering the sound radiating surface of the LF driver; and converting the electrical signal to an acoustic output at the loudspeaker, wherein the waveguide has a pattern of holes such that the acoustic output comprises an acoustic radiation pattern of the LF driver which matches an acoustic radiation pattern of the HF driver at the reference position.

In another aspect, a speaker includes: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; a waveguide covering the sound radiating surface of the LF driver; a housing defining an acoustic volume in front of the LF driver; and a Helmholtz resonator coupled to the acoustic volume in front of the LF driver.

In another aspect, a speaker includes: a High Frequency (HF) driver; a Low Frequency (LF) driver arranged coaxially with the HF driver; a waveguide covering the sound radiating surface of the LF driver; a housing defining an acoustic back volume between the LF driver and the HF driver; and a Helmholtz resonator coupled to the acoustic back volume between the LF driver and the HF driver.

Implementations may include one of the following features, or any combination thereof.

In some cases, the waveguide includes an aperture through which the HF driver is exposed.

In a particular aspect, the speaker further includes a batting positioned between the waveguide and the LF driver, wherein the batting controls cavity resonance between the LF driver and the waveguide, and wherein the batting is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.

In some implementations, the waveguide is located in front of the LF driver.

In some aspects, the waveguide includes a rigid baffle surrounding the HF drive and defining an aperture pattern.

In a particular case, the aperture pattern comprises a plurality of apertures arranged around the HF drive.

In certain aspects, energy from the LF driver is vented through holes in the hole pattern to control the beamwidth of the acoustic output.

In some cases, the waveguide includes a material for dissipating heat from the HF drive.

In a particular implementation, the speaker further comprises: a housing defining an acoustic volume in front of the LF driver; and a Helmholtz resonator coupled to the acoustic volume in front of the LF driver.

In some cases, the speaker includes an acoustic batt in a Helmholtz resonator coupled with an acoustic volume in front of the LF driver.

In some implementations, the speaker further includes: a housing defining an acoustic back volume between the LF driver and the HF driver; and a Helmholtz resonator coupled to the acoustic volume in front of the LF driver. The Helmholtz resonator may be located within the acoustic back cavity between the LF driver and the HF driver.

In some aspects, the speaker includes an acoustic flocculent in the acoustic back volume between the LF driver and the HF driver.

In certain cases, energy from the LF driver is expelled through the holes in the hole pattern to control the beamwidth of the acoustic output, wherein the speaker further comprises a batting located between the waveguide and the LF driver, wherein the batting controls the cavity resonance between the LF driver and the waveguide, and the batting is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.

Two or more features described in this disclosure, including those described in this summary, can be combined to form implementations not specifically described herein.

The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a side cross-sectional view of a speaker according to various implementations.

Fig. 2 is a top sectional view of the speaker of fig. 1.

Fig. 3 illustrates a side cross-sectional view of a speaker according to various additional implementations.

Fig. 4 is a side cross-sectional view of a speaker according to various additional implementations.

Fig. 5 illustrates an example frequency response graph showing Sound Pressure Level (SPL) versus frequency for a speaker according to various implementations, as compared to a conventional speaker.

Fig. 6 illustrates exemplary beamwidth plots for a conventional speaker and a speaker according to various implementations.

It should be noted that the figures of the various implementations are not necessarily drawn to scale. The drawings are intended to depict only typical aspects of the disclosure, and therefore should not be considered as limiting the scope of the implementations. In the drawings, like numbering represents like elements between the drawings.

Detailed Description

The present disclosure is based, at least in part, on the recognition that: the coaxial waveguide may advantageously be incorporated into a loudspeaker. For example, a speaker with a coaxial waveguide may provide a desired acoustic output in a flush-mounted or surface-mounted application.

For purposes of illustration, components generally labeled in the figures are considered to be substantially equivalent components, and redundant discussion of those components is omitted for clarity.

As described herein, a thin speaker system faces system design challenges due to the reduced spacing between its High Frequency (HF) driver (or tweeter) and Low Frequency (LF) driver (or woofer). Because many end-user applications require flush-mounted or surface-mounted speaker designs, speaker system designers must attempt to provide the required acoustic output with reduced spacing between the HF and LF drivers. Conventional approaches to solving this problem fail to control beam width at low frequencies, exhibit cavity resonances, and/or exhibit inconsistent off-axis acoustic output.

In contrast to conventional systems, the loudspeaker disclosed according to various implementations comprises an LF driver arranged coaxially with an HF driver. The loudspeaker comprises a waveguide with an aperture pattern for controlling the acoustic radiation pattern of the LF driver to match the acoustic radiation pattern of the HF driver at a reference position in front of the loudspeaker. In some cases, the sound radiation pattern of a speaker may be defined by its beam width. The disclosed speakers according to various implementations may provide consistent off-axis acoustic output, for example, at various distances peripheral to the central axis of the HF and LF drivers. The integrated waveguide configuration may improve the consistency of the acoustic output across a wide frequency range (e.g., from the low frequency cutoff of the LF driver to the alternating frequency at which the HF driver controls the loudspeaker response). In addition, the disclosed speaker according to various implementations may include an acoustic batt to control cavity resonance between the LF driver and the HF driver. In some cases, the waveguide may also act as a heat sink to cool the HF driver, allowing higher power applications with higher Sound Pressure Levels (SPL) compared to conventional systems.

Fig. 1 shows a side cross-sectional view of a speaker 10 according to various implementations, and fig. 2 shows a plan cross-sectional view of the speaker 10 according to various implementations. Reference is made to both fig. 1 and fig. 2. According to various implementations, the speaker 10 includes a housing 20 that houses a High Frequency (HF) driver 30 and a Low Frequency (LF) driver 40. In some cases, the HF driver 30 includes a tweeter, such as a dome tweeter, a cone tweeter, a piezoelectric tweeter, or the like. In one implementation, the HF driver 30 is a dome tweeter. In some implementations, the LF driver 40 includes a woofer. In some implementations, the LF drive 40 is arranged coaxially with the HF drive 30 such that the central axis of motion of the LF drive 40 coincides with the central axis of motion of the HF drive 30, as shown by axis (a) in fig. 1. However, in other implementations, the central axis of the HF driver 30 may be angled/rotated relative to the axis (a) such that the output of the speaker 10 is asymmetric.

It should be understood that both the HF driver 30 and the LF driver 40 may be coupled with one or more control circuits (not shown) for providing electrical signals to energize one or both of the

drivers

30, 40. Each

driver

30, 40 comprises a sound radiating surface for producing an acoustic output. The one or more control circuits may include a processor and/or microcontroller that may include a decoder, DSP hardware/software, etc., for playback (rendering) of audio content at one or both of the HF driver 30 or the LF driver 40. The one or more control circuits may also include one or more digital-to-analog (D/a) converters for converting digital audio signals to analog audio signals. The audio hardware may also include one or more amplifiers that provide amplified analog audio signals to the HF driver 30 and/or the LF driver 40.

The enclosure 20 defines an acoustic volume 50 in front of the LF driver 40, the acoustic volume 50 being responsive to movement of the LF driver 40 when the LF driver 40 is excited by an electrical signal. The loudspeaker 10 further includes a housing 60 defining an acoustic back volume 70 between the LF driver 40 and the HF driver 30. In some cases, the acoustic back volume 70 responds to the movement of the HF driver 30 when the driver is excited by an electrical signal. In other implementations, the HF driver 30 may include a separate back cavity sealed to its transducer so that the HF driver 30 does not interact with the acoustic back cavity 70. In any case, the housing 20 and the enclosure 60 may be formed of any conventional speaker material, such as heavy plastics, metals, composites, and the like.

A waveguide 90 covers the sound radiating surface 80 of the LF driver 40 for guiding acoustic energy from the LF driver 40 to the front face 100 of the loudspeaker housing 20. In various implementations, the waveguide 90 includes at least one aperture 110 through which the HF drive 30 is exposed. That is, the waveguide 90 includes an aperture 110 to accommodate the HF driver 30 such that the HF driver 30 is exposed at the front face 100 of the speaker housing 20.

As shown in fig. 1, the waveguide 90 is located in front of the LF driver 40. In various implementations, the waveguide 90 includes an aperture pattern 120 that includes a plurality of apertures 130 (shown as

apertures

130A, 130B, 130C, etc.) disposed around the HF drive 30. This arrangement of apertures 130 is merely one exemplary arrangement, and it should be understood that various aperture locations and/or sizes may be used, depending on various implementations. An aperture 130 extends through the waveguide 90 to allow airflow between the acoustic volume 50 and the front face 100 of the housing 20, i.e., to the environment. As described herein, in various implementations, the hole pattern 120 is configured such that the acoustic radiation pattern of the LF driver 40 matches the acoustic radiation pattern of the HF driver 30 at the reference location. In some examples, the reference position includes any position in front of the speaker of about ten (10) meters within a lateral distance defined by the coverage pattern or beamwidth of speaker 10. In some examples, the beamwidth of speaker 10 may be in a range between about 130 degrees and about 150 degrees. That is, according to various implementations, energy from LF driver 40 is discharged through

holes

130A, 130B, 130C, etc. in hole pattern 120 of waveguide 90 to control the beamwidth of the acoustic output from speaker 10.

In certain implementations, the waveguide 90 includes a rigid baffle that surrounds the HF drive 30 and defines the aperture pattern 120. That is, in some examples, the hole pattern 120 may be configured such that the center-to-center spacing between the holes 130, as measured by a line intersecting the central axis (a), is about 2 inches to about 5 inches (and, in some particular exemplary cases, about 3.5 inches). It should be understood that the various holes 130 in the pattern may have different center-to-center spacings, and that these values are merely examples of particular implementations.

In various implementations, the waveguide 90 is formed of a material for dissipating heat from the HF drive 30. In some cases, the waveguide 90 comprises a metal, such as aluminum (or an alloy of aluminum), however, in other cases, the waveguide 90 comprises another material with sufficient thermal conductivity to facilitate heat dissipation from the HF drive 30.

In some particular cases, speaker 10 also includes a batting 140 located in acoustic volume 50 between waveguide 90 and LF driver 40. Batting 140 may comprise cotton or synthetic fibers and may be attached (e.g., adhered or mounted) to the back side of waveguide 90 or to one or more walls of housing 20 or enclosure 60. In certain exemplary implementations, as shown in FIG. 1, a batting 140 is attached to the backside of waveguide 90. In various implementations, the batting 140 may help control the cavity resonance between the LF driver 40 and the waveguide 90. With the flock 140 attached to the back side of the waveguide 90, the flock 140 may be acoustically transparent at low frequencies (e.g., frequencies below the alternating frequency of the LF driver 40), but may act as a rigid acoustic boundary at high frequencies (e.g., frequencies above the alternating frequency of the LF driver 40). In addition, when batting 140 is attached to the backside of waveguide 90, batting 140 may suppress cavity resonances in acoustic volume 50 that occur at frequencies near the alternating frequency (e.g., frequencies of about 2 kilohertz (kHz)). That is, when the batting 140 is attached to the back side of the waveguide 90, it may provide a smoother (less reverberant) on-axis response from the HF driver 30, and a more consistent off-axis response from the HF driver 30.

In other cases, as described herein, batting 140 is attached to one or more walls of housing 20 and/or enclosure 60, with or without batting 140 attached to the backside of waveguide 90. The batting in these additional locations may suppress resonant vibrations in the loudspeaker 10, but may not act as a rigid acoustic boundary at high frequencies.

In operation, the control circuitry in the speaker 10 is configured to convert the electrical signal into an acoustic output at the HF driver 30 and the LF driver 40. As described herein, the hole pattern 120 in the waveguide 90 is configured such that the acoustic output has an acoustic radiation pattern of the LF driver 40 that matches the acoustic radiation pattern of the HF driver 40 at the reference location. That is, energy from LF driver 30 is discharged through holes 130 in hole pattern 120 to control the beamwidth of the acoustic output. In some cases, the batting 140 is used to control cavity resonances in the acoustic volume 50 between the LF driver 40 and the waveguide 90, such that the batting 140 is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.

Fig. 3 shows a schematic cross-sectional view of an additional implementation of a loudspeaker 300. As shown in fig. 3, speaker 300 may include a Helmholtz resonator 320 coupled with acoustic volume 50 in front of LF driver 40. In some cases, Helmholtz resonator 320 is located within the wall of housing 20 proximate LF driver 40. During operation of loudspeaker 10, Helmholtz resonator 320 may suppress cavity resonance in acoustic cavity 50. In some implementations, Helmholtz resonator 320 includes a pocket 330 of gas (e.g., air) coupled to acoustic volume 50 by a narrowed neck portion 340. In other exemplary implementations, a portion of the cavity of Helmholtz resonator 320 is filled with acoustic batting 140, and acoustic batting 140 may control the Q-factor of Helmholtz resonator 320. The Q factor is a dimensionless parameter indicative of the energy loss within the resonant element. Batting 140 may be attached to an inner surface of Helmholtz resonator 320 and may be used to match the Q-factor of Helmholtz resonator 320 to the Q-factor of acoustic volume 50 to which it is coupled.

Fig. 4 shows a cross-sectional illustration of an additional implementation of a loudspeaker 400. As shown in fig. 4, the speaker 400 may include a Helmholtz resonator 320 coupled with the acoustic volume 50 between the LF driver 40 and the HF driver 30. In some cases, Helmholtz resonator 320 is located within the wall of housing 60 behind HF driver 30. According to some implementations, Helmholtz resonator 320 is located within the wall of enclosure 60 at a location between LF driver 40 and HF driver 30, e.g., extending into acoustic back volume 70 between LF driver 40 and HF driver 30. Helmholtz resonator 320, in some cases in combination with acoustic batt 140, may be used to suppress cavity resonance in acoustic volume 50. In some implementations, Helmholtz resonator 320 includes a pocket of gas (e.g., air) coupled to acoustic back volume 70 by a narrowed neck portion (not labeled in FIG. 4). In some implementations, a portion of acoustic back volume 70 is filled with acoustic batt 140, as discussed with reference to Helmholtz resonator 320 in fig. 3.

Returning to fig. 1, it should be understood that speaker 10 may also include a Helmholtz resonator 320 in one of the positions shown and described with reference to fig. 3 and 4. These exemplary implementations are shown in dashed lines, where Helmholtz resonator 320 is coupled to acoustic volume 50 and is located in a wall of enclosure 20 (similar to speaker 300 in FIG. 3) or in a wall of enclosure 60 (similar to speaker 400 in FIG. 4).

Fig. 5 illustrates an exemplary frequency response graph showing Sound Pressure Level (SPL) versus frequency for a speaker (e.g.,

speaker

10, 300, or 400) according to various implementations and a conventional speaker without one or more waveguides (e.g., waveguide 90 or waveguide 310) described herein. Fig. 5 illustrates that the frequency response of a speaker (e.g.,

speaker

10, 300, or 400) according to various implementations has significantly less variation over a range of frequencies (i.e., the response is smoother) as compared to a conventional speaker without the waveguide described herein.

Fig. 6 illustrates an exemplary beamwidth graph for: (a) a conventional speaker without the waveguide described herein; and (b) a speaker (e.g.,

speaker

10, 300, or 400) as described in accordance with various implementations. These graphs show the variation of the beam width of each corresponding speaker with respect to frequency. As can be seen in this comparison to the conventional speaker in graph (a), the beamwidth between the high and low frequencies is significantly more consistent in graph (b), representing the response of the speaker (e.g.,

speaker

10, 300, or 400) according to various implementations.

Speakers

10, 300, and 400 may provide a thin (e.g., flush-mounted or surface-mounted) speaker configuration with consistent off-axis response and smooth on-axis high frequency response as compared to conventional speakers. For example, in some cases, the speakers described herein may provide acoustic output comparable to speakers having significantly greater depth.

It should be understood that the relative proportions, sizes, and shapes of the

speakers

100, 300, 400 and their components and features as shown in the figures included herein may be merely examples of such physical attributes of these components. That is, these proportions, shapes and dimensions may be modified according to various implementations to suit various products. For example, while a substantially rectangular speaker may be shown according to a particular implementation, it should be understood that other three-dimensional shapes may be employed for the speaker in order to provide the acoustic functionality described herein.

In various implementations, components described as "coupled" to each other may engage along one or more interfaces. In some implementations, the interfaces can include joints between different components, and in other cases, the interfaces can include solid and/or integrally formed interconnects. That is, in some cases, components that are "coupled" to one another may be formed simultaneously to define a single continuous member. However, in other implementations, these coupling components may be formed as separate components and subsequently joined by known processes (e.g., welding, fastening, ultrasonic welding, bonding). In various implementations, the electronic components described as "coupled" may be linked via conventional hardwired and/or wireless means so that the electronic components may communicate data with each other. In addition, sub-components within a given component may be considered linked via a conventional path, which may not necessarily be shown.

A number of implementations have been described. It should be understood, however, that additional modifications may be made without departing from the scope of the inventive concepts described herein, and accordingly, other implementations are within the scope of the following claims.

Claims

1. A speaker, the speaker comprising:

a High Frequency (HF) driver;

a Low Frequency (LF) driver arranged coaxially with the HF driver; and

a waveguide covering an acoustic radiation surface of the LF driver, the waveguide having an aperture pattern such that an acoustic radiation pattern of the LF driver matches an acoustic radiation pattern of the HF driver at a reference location.

2. The loudspeaker of claim 1, wherein the waveguide comprises an aperture through which the HF driver is exposed.

3. The speaker of claim 1, further comprising a batting located between the waveguide and the LF driver, wherein the batting controls cavity resonance between the LF driver and the waveguide, and wherein the batting is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.

4. The loudspeaker of claim 1, wherein the waveguide is located in front of the LF driver.

5. The loudspeaker of claim 1, wherein the waveguide comprises a rigid baffle surrounding the HF driver and defining the pattern of apertures.

6. The loudspeaker of claim 5, wherein the pattern of holes comprises a plurality of holes arranged around the HF driver.

7. The speaker of claim 1, wherein energy from the LF driver is vented through holes in the hole pattern to control a beamwidth of the acoustic output.

8. The loudspeaker of claim 1, wherein the waveguide comprises a material for dissipating heat from the HF driver.

9. The speaker of claim 1, further comprising:

a housing defining an acoustic volume in front of the LF driver; and

a Helmholtz resonator coupled to the acoustic volume in front of the LF driver.

10. The speaker of claim 1, further comprising:

a housing defining an acoustic back volume between the LF driver and the HF driver; and

a Helmholtz resonator coupled with the acoustic back volume between the LF driver and the HF driver.

11. A speaker, the speaker comprising:

a High Frequency (HF) driver;

a Low Frequency (LF) driver arranged coaxially with the HF driver;

a waveguide covering an acoustic radiation surface of the LF driver, the waveguide including a plate having a plurality of holes extending axially therethrough, wherein an acoustic radiation pattern of the LF driver matches an acoustic radiation pattern of the HF driver at a reference location; and

a batting located between the waveguide and the LF driver, wherein the batting controls cavity resonance between the LF driver and the waveguide.

12. The loudspeaker of claim 11, wherein the waveguide comprises an aperture through which the HF driver is exposed.

13. The speaker of claim 11, wherein the batting is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.

14. The speaker of claim 11, wherein the waveguide is located in front of the LF driver.

15. The loudspeaker of claim 11, wherein the plate comprises a rigid baffle, and wherein the plurality of holes are arranged around the HF driver.

16. The speaker of claim 11, wherein energy from the LF driver is vented through the plurality of holes to control a beamwidth of the acoustic output.

17. The speaker of claim 11, further comprising:

a housing defining an acoustic volume in front of the LF driver; and

a Helmholtz resonator coupled to the acoustic volume in front of the LF driver.

18. The speaker of claim 11, further comprising:

19. A method, the method comprising:

there is provided a speaker, comprising:

a High Frequency (HF) driver;

a Low Frequency (LF) driver arranged coaxially with the HF driver; and

a waveguide covering a sound radiating surface of the LF driver; and

converting the electrical signal to an acoustic output at the speaker,

wherein the waveguide has a pattern of holes such that the acoustic output comprises an acoustic radiation pattern of the LF driver that matches an acoustic radiation pattern of the HF driver at a reference position.

20. The method of claim 19, wherein energy from the LF driver is expelled through holes in the hole pattern to control a beamwidth of the acoustic output, wherein the speaker further comprises a batting located between the waveguide and the LF driver, wherein the batting controls cavity resonance between the LF driver and the waveguide, and the batting is acoustically transparent at low frequencies and acts as a rigid acoustic boundary at high frequencies.